[CRIU] [PATCH 5/8] asm: convert the ARM implementation of bit operations to the reference

[Christopher Covington]

On 03/11/2014 04:05 PM, Pavel Emelyanov wrote:
> On 03/11/2014 11:58 PM, Christopher Covington wrote:
>> Hi Pavel,
>>
>> On 03/11/2014 02:43 PM, Pavel Emelyanov wrote:
>>> On 03/10/2014 12:51 PM, Alexander Kartashov wrote:
>>>> The implementation of bit operations for ARM isn't actually
>>>> architecture-specific so it would rather be shared with
>>>> the upcoming port for AArch64 that won't provide optimized
>>>> implementation of bit operations.
>>>>
>>>> Proposed-by: Christopher Covington <cov at codeaurora.org>
>>>> Signed-off-by: Alexander Kartashov <alekskartashov at parallels.com>
>>>> ---
>>>>  arch/arm/include/asm/bitops.h |  119 ++---------------------------------------
>>>>  include/asm-generic/bitops.h  |  116 +++++++++++++++++++++++++++++++++++++++
>>>
>>> The include/asm-generic/bitops.h file makes me think this is shared
>>> between arm-s and x86, but the latter still has its own implementation.
>>
>> The x86 port _could_ use the generic version written in C, but instead brings
>> its own presumably more optimal version written in assembly. In this context,
>> I interpret your question to fundamentally be, "Which architecture ports use
>> the generic implementation?"
> 
> Yes.
> 
>>> Maybe we can put this file into arch/ and share it between arm and arm64?
>>
>> The location of the file should not affect its ability to be included/used by
>> any architecture port. As for the first part of the question, how does moving
>> it to arch/ (which I believe would be a deviation from the Linux kernel layout
>> that some might expect) answer the question above?
> 
> Ah, I see. So the intention is to include this file only from arch/include/
> in case architecture wants C-bitops. Well, OK, this makes sense to me. I'll
> add a comment into asm-generic/bitops.h saying that this file is not for
> inclusion from anywhere but arch/include/bitops.h

Sounds helpful. arch/$ARCH/include/asm/bitops.h to be precise.

Christopher

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by the Linux Foundation.